What if the ether wind happens to be coming directly from above?
Yes, if the ether wind happens to be coming from directly above, exactly perpendicular to the plane of the experiment, then you’re out of luck, since there will be no wind-induced time of flight difference in that case. But the experiment is on the surface of the Earth, which is rotating… and the Earth is going around the Sun, and the Sun around the center of the Galaxy, so it’s hard to imagine that you’d have an exactly orthogonal wind all the time!
